Fix check for `delete_url_name` attribute in generic `DeleteView`

Fixes #9861

CHANGELOG.txt

@@ -54,6 +54,7 @@ Changelog
  * Fix: Close the userbar when clicking its toggle (Albina Starykova)
  * Fix: Add a border around the userbar menu in Windows high-contrast mode so it can be identified (Albina Starykova)
  * Fix: Make sure browser font resizing applies to the userbar (Albina Starykova)
+ * Fix: Fix check for `delete_url_name` attribute in generic `DeleteView` (Alex Simpson)
  * Docs: Add custom permissions section to permissions documentation page (Dan Hayden)
  * Docs: Add documentation for how to get started with contributing translations for the Wagtail admin (Ogunbanjo Oluwadamilare)
  * Docs: Officially recommend `fnm` over `nvm` in development documentation (LB (Ben) Johnston)

CONTRIBUTORS.rst

@@ -680,6 +680,7 @@ Contributors
 * dr-rompecabezas
 * Rishabh jain
 * Jhonatan Lopes
+* Alex Simpson
 
 Translators
 ===========

docs/releases/4.2.md

@@ -78,6 +78,7 @@ This feature was developed by Jake Howard.
  * Close the userbar when clicking its toggle (Albina Starykova)
  * Add a border around the userbar menu in Windows high-contrast mode so it can be identified (Albina Starykova)
  * Make sure browser font resizing applies to the userbar (Albina Starykova)
+ * Fix check for `delete_url_name` attribute in generic `DeleteView` (Alex Simpson)
 
 ### Documentation
 

wagtail/admin/views/generic/models.py

@@ -652,7 +652,7 @@ class DeleteView(
         return str(self.object)
 
     def get_delete_url(self):
-        if not self.index_url_name:
+        if not self.delete_url_name:
             raise ImproperlyConfigured(
                 "Subclasses of wagtail.admin.views.generic.models.DeleteView must provide a "
                 "delete_url_name attribute or a get_delete_url method"